Pressure actuated door

ABSTRACT

The invention is a flow control for a ventilation duct. It includes a movable panel which is attached to a variable volume reservoir. The application of vacuum to the reservoir controls the angular position of the door and the volume of the reservoir.

TECHNICAL FIELD

The invention relates to air flow control structures used for heatingand cooling systems, and more particularly to a pressure operated doorfor use in controlling ventilation air flow in an automobile.

BACKGROUND ART

Modern automobiles have complex ventilation systems which includeair-cooling and air-heating units. Typically, rigid doors are providedwithin the duct work to control and direct the passage of air. Usually,the doors are mounted on a door axle which is rotated by a vacuumactuator located on the exterior surface of the duct work. Morerecently, it has been proposed to integrate a bellows type actuator withthe door structure. However, such devices are bulky and prone tofailure.

SUMMARY DISCLOSURE

According to the invention, several rigid panels 26,28,30,32 are linkedtogether with hinges to form a polygonal linkage. The panels along witha first side wall 34 and a second side wall 36 define a closed reservoir22. The volume within this reservoir 22 is variable and depends upon thevarious angles between the various panels which make up the reservoir22. A vacuum drawn in the reservoir 22 causes ambient air pressure tocollapse the reservoir by reducing the interior volume of the reservoir22 due to the movement of the linked panels.

Reduction of the volume of the reservoir is accompanied by movement ofthe panels. One of the panels such as panel 30 may form a portion of adoor assembly 10. Consequently the application of vacuum to thereservoir 22 causes the door assembly 10 to move from a first positionto a second position.

The panels and hinges are illustratively arranged to produce anasymmetrical trapezoidal shape for the polygonal linkage. This asymmetrycauses the linkage to move in a preferred direction as the reservoirvolume is reduced. The integration of the linkage into the doorstructure provides a compact space efficient assembly which has a longservice life and which may be readily designed into an automotiveventilation system.

BRIEF DESCRIPTION OF THE DRAWINGS

An illustrative and exemplary embodiment of the invention is shown inthe various figures. Identical reference numerals refer to identicalstructure throughout.

FIG. 1 is a perspective view of the door assembly.

FIG. 2 is a cross-section of the door assembly.

FIG. 3 is a perspective view of the door assembly.

FIG. 4 is a cross-section of the door assembly.

FIG. 5 is a front view of the door assembly in isolation.

FIG. 6 is a side view of the door assembly in isolation.

FIG. 7 is a front view of the door assembly in isolation.

FIG. 8 is a side view of an alternate door construction.

FIG. 9 is a detail side view of an alternate door assembly.

FIG. 10 is a perspective view of a valve mechanism for positioning thedoor assembly.

FIG. 11 is a side view of a valve mechanism for positioning the doorassembly.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the door assembly 10 located in a plenum 12 of anautomotive ventilation duct 14. The ventilation duct 14 includes anopening 18 and an opening 19. In FIG. 1 the door assembly 10 is in theactuated state which defines a "first position" for the door panel 30.In this position subatmospheric pressure is present in the interiorvolume 20 of the reservoir 22 which makes up a portion of the doorassembly 10. Air pressure in the reservoir portion of the door assemblyis controlled by a remote vacuum source 17 which is connected to thedoor assembly through a valve 15 and a vacuum line 16.

The door assembly 10 includes several panels. In the embodiment shown inFIG. 1, the door assembly includes panel 26, panel 28, door panel 30,and stationary base panel 32. Panel 26 is Joined to base panel 32 with ahinge 27. Panel 26 is joined to panel 28 by hinge 29. Panel 28 is joinedto the door panel 30 by hinge 31. The door panel 30 is attached to basepanel 32 through hinge 33. Together these four panels and associatedhinges form a polygon linkage 37 seen best in FIG. 2 or FIG. 4. Pleatedbellows structures may be used for side wall 34 and side wall 36. Theside walls are required to close off the polygon linkage to form theinterior volume 20 of the reservoir 22, defined by the panels and sidewalls.

FIG. 2 shows the door assembly 10 in the actuated position where thedoor panel 30 blocks off an opening 18 in the ventilation duct 14. Inthis cross-section view the interior volume 20 of the reservoir 22 isseen in the minimum volume configuration. The subatmospheric pressurewithin the reservoir 22 causes the return spring 24 to be compressedbetween panel 26 and door panel 30, as the door assembly 10 rotates inthe clockwise sense as indicated by arrow 38. This is the maximum energystate for the door assembly 10. In this view it should be appreciatedthat the base panel is attached to an interior surface of theventilation duct 14. Consequently only this panel remains stationarywith respect to the ventilation duct 14 as the volume of the reservoir22 changes.

FIG. 3 shows the door assembly rotated into the relaxed state whichdefines a "second position" for the door panel 30. Motion in thecounterclockwise direction is indicated by arrow 40. This motion occurswhen near atmospheric pressure is admitted to the reservoir 22 throughthe vacuum line 16.

FIG. 4 shows the door assembly 10 in the second position. In thisinstance the return spring 24 supplies force between door panel 30 andpanel 26. In this minimum energy state the size of the interior volume20 of the reservoir 22 is at its maximum. In this second position thedoor panel 30 in abutment with the plenum 12 closing off an opening 19.In this position the door panel 30 blocks off opening 19 and opensopening 18. One should note that this plenum wall limits continuedmotion in the counterclockwise direction. This figure also shows thebase panel 32 most clearly and also shows the aperture 42 which connectsthe vacuum line 16 with the interior volume 20 of the reservoir 22.

Comparison of the area confined between the panels in FIG. 2 to the areashown in FIG. 4 reveals that the size of the interior volume 20 tends toincrease as the door assembly 10 rotates in the counterclockwisedirection in the sense of the figure. Assuming that the door assembly 10is in the minimum energy state and the panel dimensions and angles havebeen selected so that the reduction in reservoir volume fromdisplacement in the clockwise direction exceeds reduction in reservoirvolume from displacement in the counterclockwise direction then thepanel will prefer to rotate in the direction resulting in the greatestreduction of volume. By selecting asymmetrical panel dimensions toachieve this volume change effect the door assembly 10 can be biased toprefer rotation in the clockwise direction upon the application ofsubatmospheric pressure via vacuum line 16.

FIG. 5, FIG. 6 and FIG. 7 should be considered together. These drawingsdepict the door assembly 10 in isolation and show a form of constructionwhich uses a number of "living hinges" on a unitary molded part to formthe panels and side walls.

FIG. 8 depicts an alternate and preferred form of door assembly 46construction. In this embodiment the first door panel 48 is connected toa second mounting panel 50 by an elastomeric hinge 52. The third basepanel 54 is likewise hinged to the second mounting panel 50 with anelastomeric hinge 56. The fourth actuator panel 58 is hinged viaelastomeric hinge 60 to first door panel 48. It is desirable to supply acoil type restoring spring 74.

The relatively rigid panels along with the elastomeric hinges provides astructure which is capable of moving the first door panel 48 throughapproximately ninety degrees of rotation.

FIG. 9 is a detail side view of an alternate door assembly which can bepositioned in an "intermediate" position between the first position andthe second position. In this embodiment two air passages are provided.The first passage 62 is connected to a first orifice 64 whichcommunicates with the reservoir 22. A small leaf type valve spring 66 isattached to the base panel 54 and moves into abutment with the firstorifice 64 as the door assembly moves through arc 68. When a vacuum isdrawn at first air passage 62 the door assembly 10 will rotate throughthe arc 68 until the first orifice 64 is covered by the leaf type valvespring 66. Any leakage will cause the orifice to become uncovered thusrepositioning the door in the intermediate position. If full motion isdesired, vacuum can be applied to the second air passage 70. The secondorifice 72 which communicates to the reservoir 22 from second airpassage 70 is not obstructed by the valve spring 66 and thereforepermits the full range of door motion into the second position. Thelight restoring force supplied by the valve spring 66 does not preventthis motion.

In some applications it may be preferably to operate the door assemblywith positive pressure. In these applications the spring 66 would bearranged to bias the reservoir into the minimum volume state. Theapplication of super atmospheric pressure would then move the doortoward the maximum volume state.

FIG. 10 and FIG. 11 show a rotary valve assembly 76 which may be used insome automotive applications where it is desirable to stop the doorpanel at intermediate positions. The rotary valve assembly includes anannular control ring which is concentrically mounted on the periphery ofa rotary piston 80. The rotary piston is connected to a tube 82 which ismounted for rotation with the door panel 30. The tube includes aninterior passage which permits fluid communication between the interiorvolume 20 of the reservoir 22 with the port 84 formed on the peripheryof the rotary piston 80. In operation the user selects the desiredposition for the door by rotating the control ring 78 to a correspondingannular location. Conventionally such automotive controls use a movablewire 86 which can be moved by a user actuated control lever. Motion ofthe movable wire 86 along path 88 rotates the control ring to a userselected position. Vacuum is supplied to the reservoir through the port84. In general, the return spring 24 will supply force which will movethe door 30 along path 90 causing the port 84 to rotate in thecounterclockwise direction indicated by path 92. However the vacuumsupplied via the tube 82 from the vacuum line 16 causes the door 30 tomove in the clock wise direction. The resultant action is that the doorremains in the position defined by the annular location of the slot 94.

What is claimed is:
 1. A door assembly for controlling air flow througha ventilation duct, said door assembly of the type having a reservoirand a movable panel; wherein the improvement comprises:a tube connectedto said movable panel and communicating with said reservoir; a rotarypiston coupled to said tube and having a port which communicates withsaid reservoir; and an annular control ring mounted concentric with saidrotary piston and having a slot in communication with a source ofpressurized fluid, whereby the position of said slot with respect tosaid port determines the position of said door panel.